A high strength Al–Li alloy produced by laser powder bed fusion: Densification, microstructure, and mechanical properties

Qi, Ying; Zhang, Hu; Nie, Xiaojia; Hu, Zhiheng; Zhu, Haihong; Zeng, Xiaoyan

doi:10.1016/j.addma.2020.101346

Cited by 18 publications

(23 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It stands to reason that, although dislocations induced by the large amounts of residual stress in the as-built condition, which could have acted as potent T 1 nucleation sites, T 1 nucleation and growth could not possibly have taken place without sufficient time and appropriate temperature. This is consistent with work done by the authors of Reference [ 21 ], who found high-density dislocations in the as-built sample with no formed T 1 phases, but reportedly found T 1 only after T6 heat treatment of the LPBF processed Al-Cu-Li alloy. Through appropriate LPBF preheat treatment (in combination with dissociated dislocation spots which act as nucleation sites), T 1 phase formation can be achieved through the LPBF process.…”

Section: Resultssupporting

confidence: 92%

“…In the as-built microstructure, cracks were observed ( Figure 3 ), which are attributed to residual stress build-up. TEM investigations showed dislocations with no detection of the T 1 phase, consistent with observations in Reference [ 21 ]. This confirms the conventional view that T 1 , even at dislocation sites, still finds it difficult to nucleate without appropriate time and heat treatment temperatures.…”

Section: Discussionsupporting

confidence: 91%

“…This is also evidenced by the slightly higher T 1 volume fraction recorded at the 500 °C preheat treatment temperature and confirms our earlier work [ 20 ] on AM (LPBF)-processed AA2099 Al-Cu-Li alloy, where increased microhardness was attributed to the strengthening effect of the T 1 phase after 520 °C preheat treatment temperature. The authors of Reference [ 21 ], after LPBF processing of AA2195 and performing a T6 thermal treatment, also attributed improvement in mechanical properties to the T 1 phase. The T B phase is, however, in this work, reported for the first time in an AM (LPBF)-processed Al-Cu-Li alloy, although its strengthening effect is regarded as not significant.…”

Section: Resultsmentioning

confidence: 99%

“…The alloy’s recorded microhardness was suspected to be due to the presence of the T 1 phase, although no phase characterisation was performed. In a recent work carried out by the authors of Reference [ 21 ] on LPBF processability, microstructure and mechanical properties of an AA 2195 Al-Li alloy, the authors focused on as-built (no preheating) and T6 post-heat-treated conditions. They also attributed mechanical properties to T 1 precipitates.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Characterising the Microstructure of an Additively Built Al-Cu-Li Alloy

et al. 2020

View full text Add to dashboard Cite

Al-Cu-Li alloys are famous for their high strength, ductility and weight-saving properties, and have for many years been the aerospace alloy of choice. Depending on the alloy composition, this multi-phase system may give rise to several phases, including the major strengthening T1 (Al2CuLi) phase. Microstructure investigations have extensively been reported for conventionally processed alloys with little focus on their Additive Manufacturing (AM) characterised microstructures. In this work, the Laser Powder Bed Fusion (LPBF) built microstructures of an AA2099 Al-Cu-Li alloy are characterised in the as-built (no preheating) and preheat-treated (320 °C, 500 °C) conditions using various analytical techniques, including Synchrotron High-Energy X-ray Diffraction (S-HEXRD). The observed dislocations in the AM as-built condition with no detected T1 precipitates confirm the conventional view of the difficulty of T1 to nucleate on dislocations without appropriate heat treatments. Two main phases, T1 (Al2CuLi) and TB (Al7.5Cu4Li), were detected using S-HEXRD at both preheat-treated temperatures. Higher volume fraction of T1 measured in the 500 °C (75.2 HV0.1) sample resulted in a higher microhardness compared to the 320 °C (58.7 HV0.1) sample. Higher TB volume fraction measured in the 320 °C sample had a minimal strength effect.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Characterising the Microstructure of an Additively Built Al-Cu-Li Alloy

et al. 2020

View full text Add to dashboard Cite

show abstract

“…This is similar to the LPBFed Ti-modified Al-Cu-Mg alloys and Zr-modified Al-Cu-Mg alloys [55,61]. The average misorientation angles around the measured point are 42.04°, which can be used to calculate the geometrically necessary dislocations (GNDs) density ρ GND [62,63]:…”

Section: Grain Structuresupporting

confidence: 62%

Synchrotron Characterisation of Ultra-Fine Grain TiB2/Al-Cu Composite Fabricated by Laser Powder Bed Fusion

Cai

Duan

et al. 2021

Acta Metall. Sin. (Engl. Lett.)

View full text Add to dashboard Cite

Isotropy in microstructure and mechanical properties remains a challenge for laser powder bed fusion (LPBF) processed materials due to the epitaxial growth and rapid cooling in LPBF. In this study, a high-strength TiB2/Al-Cu composite with random texture was successfully fabricated by laser powder bed fusion (LPBF) using pre-doped TiB2/Al-Cu composite powder. A series of advanced characterisation techniques, including synchrotron X-ray tomography, correlative focussed ion beam–scanning electron microscopy (FIB-SEM), scanning transmission electron microscopy (STEM), and synchrotron in situ X-ray diffraction, were applied to investigate the defects and microstructure of the as-fabricated TiB2/Al-Cu composite across multiple length scales. The study showed ultra-fine grains with an average grain size of about 0.86 μm, and a random texture was formed in the as-fabricated condition due to rapid solidification and the TiB2 particles promoting heterogeneous nucleation. The yield strength and total elongation of the as-fabricated composite were 317 MPa and 10%, respectively. The contributions of fine grains, solid solutions, dislocations, particles, and Guinier–Preston (GP) zones were calculated. Failure was found to be initiated from the largest lack-of-fusion pore, as revealed by in situ synchrotron tomography during tensile loading. In situ synchrotron diffraction was used to characterise the lattice strain evolution during tensile loading, providing important data for the development of crystal-plasticity models.

show abstract